This invention relates to a fill and relief valve arrangement particularly adapted for the introduction of fluid into and the selective venting of fluid from a variable volume chamber of a hydraulic track adjuster.
Hydraulic track adjusters used on crawler tractors between the recoil spring and the idler commonly have a variable volume fluid chamber into which grease or oil is added to extend a piston or rod for tightening the track chain to compensate for wear to the track components. Many such track adjusters include a fill valve for adding pressurized fluid to the chamber and a separate relief valve for venting the chamber in preparation for disassembling the track chain or other track components. Occasionally, rocks, dirt, mud, etc. will become lodged between the track and idler and/or sprocket causing the recoil spring to be compressed and generating tremendous fluid pressure in the fluid chamber. To prevent the fill valve from being expelled by the pressurized fluid should it be removed without first venting the pressure, various devices have been employed to insure that the fluid pressure in the chamber is relieved prior to disassembling the track adjuster. Such devices include the addition of retainer shields to prevent the complete removal of the fill valve or relief valve until the pressure is relieved or the addition of bleed holes to vent the chamber to the atmosphere before either the fill valve or relief valve is removed, or a combination of both devices. Although these devices have been highly successful in alleviating the above problems, they are not readily adaptable to some types of hydraulic track adjusters.